NEW YORK — On the eve of National Missing Children’s Day, police said they’d at last cracked the case that started it — the 1979 disappearance of 6-year-old Etan Patz.

After decades of inconclusive clues and stalled hopes, a former convenience-store stock clerk was arrested Thursday on a charge of murdering Etan, one of the first missing children ever to appear on a milk carton. He vanished while walking to his school bus stop alone for the first time on May 25, 1979 — the date President Ronald Reagan designated four years later for missing children to be remembered.

Pedro Hernandez, 51, told investigators this week he lured the little boy into the shop with the promise of a soda, then led him to the basement, choked him and put his body in a bag with some trash about a block away, Police Commissioner Raymond Kelly said. Investigators hadn’t determined any motive, he said.

Kelly said there is no physical evidence. But authorities say they have a detailed, signed confession, as well as accounts of incriminating remarks Hernandez made to others.

A law enforcement official told The Associated Press that Hernandez was taken to a hospital for a psychological examination early Friday. The official wasn’t authorized to speak publicly about the investigation and spoke on the condition of anonymity.

While the arrest marked only the start of what could be a complex court case, it was a stunning turn in one of the nation’s most tortuous and baffling missing-children cases. Police had been aware of Hernandez, as the shop was in Etan’s neighborhood, but had never before eyed the married father as a suspect. Another man had long been the prime suspect, and investigators questioned yet a third man as recently as last month.

All the while, Stan and Julie Patz have stayed in same downtown Manhattan apartment, never even changing their phone number in case their vanished son tried to call.

“We can only hope,” Kelly said, “that these developments bring some measure of peace to the family.”

The Patzes and a lawyer for them didn’t immediately return calls Thursday.

At Hernandez’s home in Maple Shade, N.J., no one answered the door Thursday night. Neighbors said they were surprised at his arrest.

“I knew the guy. He was not a problem. His family was great people,” said Dan Wollick, 71, who rents an apartment in Hernandez’ home. “He didn’t bother anybody.”

The arrest — the first ever in the case — was a long-sought grail for authorities, including Manhattan District Attorney Cyrus R. Vance Jr., who announced he was renewing the investigation shortly after he took office in 2010.

His office, which declined to comment Thursday, will now move on to the work of prosecuting a 33-year-old case in which no body has ever been found. Prosecutors will likely look to amass witness statements or other evidence to support Hernandez’ account.

Etan vanished in New York’s busy SoHo neighborhood, which was edgier then than the swath of chic boutiques it is now.

Police conducted an exhaustive search amid a crush of media attention. Thousands of fliers of the sandy-haired boy with the toothy grin were plastered around the city. Buildings were canvassed and hundreds of people interviewed.

The disappearance ushered in an era of anxiety about leaving children unsupervised.

Detectives are often inundated with hoaxes, false leads and possible sightings around the anniversary. But Kelly said they had probable cause to believe Hernandez’s story was true, because of specific details he gave to police.

Hernandez, who had worked at the convenience store for about a month and lived nearby, wasn’t questioned at the outset, Kelly said. Days after Etan vanished, Hernandez left that job and moved to New Jersey, where he had relatives, the commissioner said.

Hernandez worked in construction until he suffered a back injury in 1993 and has since received disability payments, Kelly said. He said Hernandez, who has a teenage daughter, had no criminal record.

But he told a relative and others, as far back as 1981, that he had “done something bad” and killed an unnamed child in New York City, according to Kelly. Police learned that only recently, when a tipster — not a relative — pointed police to Hernandez, after a search of a basement near Patz’ home last month hurtled the case back into the news, Kelly said.

Police took him into custody Wednesday night, and after several hours of questioning, he provided a signed confession, Kelly said.

“He was remorseful, and I think the detectives thought that it was a feeling of relief on his part,” the commissioner said.

Earlier leads had arisen and stalled, at one point taking investigators as far as Israel to track reported sightings of Etan.

For most of the past decade, the investigation focused on Jose Ramos, a convicted child molester now in prison in Pennsylvania. He had been dating Etan’s baby sitter.

A civil judge found him to be responsible for the boy’s disappearance and presumed death, largely because he refused to answer some questions under oath, but he was never criminally charged. He might be able to get the civil judgment reviewed now.

A few weeks ago, investigators excavated a basement down the street from the Patz apartment but found no human remains. They questioned a handyman who had a workspace in the cellar in 1979. But he was not named as a suspect and denied any involvement in the boy’s disappearance.

Finally, on Thursday, police told Patz’ parents they had honed in on Hernandez.

“Mr. Patz was taken aback, a little surprised, and I would say overwhelmed, to a degree,” Lt. Christopher Zimmerman said. “ ... He was a little surprised, but I think after everything Mr. Patz has gone through, he handled it very well.”

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Associated Press writers Deepti Hajela, Tom Hays and Karen Matthews in New York and Geoff Mulvihill in Maple Shade, N.J., contributed to this report.

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